Wheel-brake.



H, A. STEEN.

WHEEL BRAKE APPLICATION FILED 06113.20, 1908 1,125,159 Patented Jan. 19, 1915.

"I \NHNESSESI q I I INV TOR BY W W a AfTORNEY am". it .ILLA

HARRY A. SIREN, or PITTSBURGH, rnnnsrnvsnrie, essrenon, BY MEsnE ASSIGN- MENTS, TO XVESTIE enccsn ELECTRIC Ann mmmrncrnalne COMPANY, or EAST PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

Specification of Letters Patent.

Ila,

To all whom it may concern."

Be it known that I, lliimrr A. Smart, subject of the King of Norway, and a rcsident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have in-' vented a new and useful Improvement in \V-heel-lira-kes, of which the following is a specification.

My invention relates to wheel brakes" and 'contact' shoes therefor, and it has for its object to provide an improved device of this character that shall be simple and duralole' in con'structionand adapted to produce a maximum braking effect with a minimum amount of applied power.

When electric driving motors are used with elevators and hoists, it is desirable to provide a braking device by which the mo tor is promptlym'nd automatically brought to rest upon the interruption of the electric supply circuit connections or in case of accident to the mechanical parts. This re suit is usually accomplished by providing a spring or some similar mechanical means for applying the brake and an electro responsive device for releasing the brake.

Band brakes havefbeen employed for these purposes but equal retarding forces have not hcretoforebeen obtained for both directions of motor rotation withont sacrificing the cfiiciency of the brakes. The effectiveness of band brakes is, however, well known and my improved device is of this general type, the structural details being designed to avoid the diiflculties of the prior art.

It has been my aim to so improve the structure of the contact member of the brake thata greater retarding effect may be obtained by means of a'mnch weaker spring, thereby permittingthe use of a much cheaper" and lighter electro-rnagnet for releasing tlie brake. Those familiar With the art will understand that the cost of the release magnet largely determines the cost of the whole device, since the mechanical features of the brake are usually simple and inexpensive,

My improved stationary contact-member comprises, in generaL -asingle shoe of cast iron or similar materialg-which is in the form of aninterrupted ring, and is'adapted to engage all but very small part of the circumference of the wheel when the brake is applied. The contact surface of the shoe is so finished that its diameter is slightly greater than that of the wheel,-. tlieieby causing the shoe to readily release itself'from the outer surface of the wheel as soon as the pressure tending to apply the brake is relieved. A steel band is wrapped completely around the outside of theshoe, to which it is secured, the ends of the band being crossed and secured to levers through wlnch forces are transmitted for bringing the cast .iron shoe into engagement with the wheel; I v

While itis, of course, desirable to reduce the current required to operate direct current' brake magnets, it is of much greater importance with alternating currentbrake magnets for the following reasons The inductive resistance of the alternating ctir rent nnignet prohibits a series connection between the motor and the magnet and, consequently, the energy required for the magnet is an additional load on the supply circuit. This additional load is particularly heavy when the motor is started and when the air gap of the brake magnet is'a maximum;furthermore, the effect on the power factor of the load is greater or less according to the percentage of the total load required for the magnet.

Figure 1 of the accompanying drawings,

'is a side ciivation of a brake constructed in accordance with my invention. Fig. 2 is-an cndclevation of the brake shown in Fig. l, and Fig. 3 is-a perspective View of a portion of the steel band whiclrforms a part of the contact member of the brake.

Referring to the drawings, the device'here illustrated comprises a stationary bracket 2, which is adapted to be securedto the frame 3 and 6' which are pivoted at intermediate points in their lengths upon the stationary bracket 2, a brake wheel 7, which is mounted on the shaft 8- of the electric-motor 4,-

a shoe 9, which engages the outer surface 100 of the wheel 7, a steel band 10, which is wrapped completely around the shoe 9- and v is secured to it by bolts 10% :1, spring ll, byj'which the brake is; applied, andan elecbreke, when energize.

fro-magnet 4%, which acts to release 105 5c so of an electric motor 4, levers 5 or, wt)

The whee ET is preferably provided with a plurality of? vanes or projections 12, which tend to in'iproi'e its ventilation. 'l he and G are fuleriiinetl near their initi upon stationary sh at their lower out. iiihieh is under b g secure i 015 the steel .ueaos pull eriorttl by the ends of the ltlllti tenth 1 Toto eiigagemei'it with tl e oute' :ie Wheel '2. order to maintain the elzsireil relation. bet ween the SQVGlItil parts ot the hr; he when it applied to the motor, under high speed or slow speetl conditions oil? operation, in. i direction. the bracket provided with projections it and 15, that constitute ri gitl stops for the levers and 6 and take the reaction priiitlueetl by the retarding forces" it will be understood that, While the spring pressure may be relatively slight, the tension on the band 10 is very great, when tl'ie brake is in ope ation and. the Wheel 7 is rotating, and this high tension would. iieeessitate a relatively lirwy and cfi'u'ubeisoii'ie lOTGl. construction. except for the fact that the stops it and are so locate as to em a the levers very close to their points of i: ,olll 'jll with the ends of the band. Since the stops are 83 11111126 ieally a'ri'ai'igecl anti amt similarly :tor oppc ite directions of wheel. rotation, the bri" structure is .r-

ulaiily well adapted. for use with rotating frequently reversed ill til levers Y he raiily removed and replaced ".lfhe llil'tlitl may be rele: seal by energizing the electro-iuagiiet 1i ti'liioh. "to its force, through it connecting rod 16, upon one end of a hell crank lever 11 that is pivoted. upon the upper end of the lever t3 and the other entl oil which connected to the corresponding; end. the levee 5 by means oil a .rotl 18. The barn i0 is prot'itletfl with a slot 19 at one en ough whieh the narrow opposite lltl promote.

The elem, o-iniig'iiet may be oi any euitable (lesigii. 'u l'iiel'i will. be (l0i1BlHllIl(f(l by the e" .eter oil the eiiergy which is apolieti to its windings, the magnet illustrated. in the drawings comprising a pair of E shaped more members 20 and 21, magnet coils and. and. a frame struetui'e 52 1. The core moist be A is pivoted. a pen a shaft which projects laterally from an arm 2;) of the bracket 'lhe eoi'e member 91 is movable relative to the core IflCll'ii'JQ Q0 and is seeur. I to one end of the connecting real 16. The arrangement oil? the parts such that the free entls oi. the core strueturo are slightly i-aepai'atetl rtliei the brake :pplieti iiitl are close to a the:

momma the shoe.

is CUllCJC 'al' le that siriwtural iiietlilimt- Lions iiia hi r l ithin the spirit .seope o I claim). as .t. The eoi'i'ibination with a brake Wheel 2i cylind ical rim si'ii-l'aee Ulil stalei'ers .fi'ilerameti at, iuterimirliate Points leeateii one at each "do elf the wlaieh of a single shoe eeueeutifie with the riiii of the wheel and slightly st J'tl'ttl13ll .l'ron'i its surface, a hand wra igietl about the shoe and. SGCillGCl thereto, anti 1116:]!55 :tor exerting equal and opposite threes on the levers to spring; the shoe into engagement with the poii loeatetl one at each side of the wheel, oil a single shoe eoueei'itrio with the rim of the. wheel and slightly se ziii'zi'ijecl from its surface, it bane W1: rppeil about the shoe and eeeiiiecl thereto, anti a tension spring cow meeting eerrespending ends of the lovers to tore-e the shoe into ei'iga jgoiiient with the the mile of salt]. baud being crossed ei'iiiil'iii'iatioii Wit. a brake wheel, of a shoe atlii itetl to engage the major "on. of t .io Wheels oii'euiii eieiiem av hand. oped r tual the shoe, I V maintaining a eoiocei'itrie relation between the shoe and.

the wheel when. the bral ze released and means for exerting tei'isional forces on. the baud. to spring the shoe into engagement Witl'i. the Wheel, tl'iei'nner diameter of the shoe being slightly greater than the outer tliaiiieter the wheel 4:. The combination with a, brake wheel anti y levers luleruiiietl at intermediate points and loeatetl one each side on the lovers to e )iiiw the shoe into eneam l'i'lGl'll; with the Wheel, the ends of the said hand being CLUH l and secured. to the lovers.

:3. A ion with. a, b 'alte wheel aii ers fiileruinetl til) iiitoi located at (iiamotrieally its concentric with the rim of the opposite sides of the wheel, of a single shoe Wheel and slightly separated from its surface, a hand Wrapped about the shoe and secured thereto, stationary stops disposed between corre sponding ends of tl; levers and the rim of the Wheel for limitin the movement of the levers and a spring joining the opposite ends of levers for forcing the shoe into engagement with the wheel, the ends of the band being'crossed and secured to the levers.

6. A brake comprising a Wheel, a contact band Wrapped about the Wheel, levers pivotof the Wheel and respec ed one on each side tively connected to the ends of the hand, a

springconnecting corresponding ends of the lovers for applying the band to the Wheel, means for actuating said levers to release the band from the Wheel, and stops for limiting-the movement of the levers in order to resist the braking action in either direction of Wheel rotation.

7. The combination with the brake wheel of levers iulcrumed at substantially (liametrically opposite points of said. wheel, a single shoe adapted to engage said wheel, a band secured to and wra med around said shoe, the ends of said hand being crossed and secured to corresponding ends of said levers a tension spring connecting the opposite ends of said levers, and means to move said levers against the tension of said springs.

In testimony whereof, I have hereunto subscribed my name this 15th day of Oct, 1908.

titer A. srrlnis.

Witnesses R. J. Dnaneonn, Burner Hines. 

